ruby

ruby
A purely object-oriented scripting language. This language is a relative newcomer, but it is rapidly gaining popularity, and may well be the flavour of the future of programming.

To write a simple program in ruby, I open my favorite text editor and start a program with the following first line:
#!/usr/bin/ruby

Here is an example of a program that I wrote to help me understand the basics of the ruby language:
#!/usr/bin/ruby
#This is a comment
a = Array.new
print "Please enter a few words (type EXIT to stop):\n"
i = 0
while enterWord = STDIN.gets
enterWord.chop!
if enterWord == "EXIT"
break
end
a[i] = enterWord
i += 1
end
#sort the array
for i in 0...a.length-1 do
for j in i+1...a.length do
if a[j] < a[i]
tmp = a[i]
a[i] = a[j]
a[j] = tmp
end
end
end
#Output the results
print "You entered "  + a.length.to_s + " entries.\n\n"
for i in 0...a.length do
print "Entry " + (i+1).to_s + ": "+ a[i] + "\n"
end

I save my ruby script to file "myprogram". To execute it, I need to type on the command line:
./myprogram

C

gcc filename.c
GNU C compiler. Quite straight-forward if you know C. Extensive free manuals are available on the net.

How do I compile a simple C program?

Start your favourite text editor and type in your source code. For example, I may use pico:
pico hello.c
and type in the Kerningham and Richie (the creators of "c") intro example of a C program:
#include <stdio.h>
void main(void) {
printf("hello world\n");
}
I save the file and then invoke the GNU C compiler to compile the file "hello.c":
gcc hello.c
The gcc compiler produces an executable binary file "a.out", which I can run:
./a.out

C++

g++ filename.C
GNU C++ compiler. The capital "C" is often used for C++ sources.  If you need an "integrated development environment" (IDE), kdevelop is really something you would probably like to look at.

How do I compile a simple C++ program?

Just like in c, I open a text editor and write my program. For example, using pico, I write the following program:
//This is a comment (to the end of line, C++ style)
#include <stdio.h>
#include <math.h>
#include <iostream.h>
#include <stdlib.h>
//define a function
double wheeldrop (double dGap, double dDiameter) {
double dDrop, dRadius, dNotDrop;

    dRadius = dDiameter * 0.5;
dDrop = dRadius - sqrt( (dRadius*dRadius)-(0.25*dGap*dGap) );

    return (dDrop);
}   //end of the function

//The function main is the entry point to the program
void main(void) {
double dGap, dDiameter, dDrop, dRadius, dNotDrop;  //variables

    for (;;) {                                         //infinite loop
cout << "Please enter gap between track segments and \n"
<< "diameter of train wheel in inches (-1 -1 to exit): ";
cin >> dGap >> dDiameter;

        if ((dGap == -1) && (dDiameter == -1))
break;
else if (dGap < dDiameter) {   //do calculations
dDrop = wheeldrop (dGap, dDiameter);
printf ("The wheel will drop %f inches.\n\n", dDrop);
}
else {
printf ("Error, your train is going to crash.\n Gap bigger then wheel!\n\n");
}
}
}

I save the source to the file "train.c", and then invoke the GNU C++ compiler to compile the file "train.c" to an executable called "traincalc":
g++ -o traincalc train.c
I can then run the executable by typing:
./traincalc

kdevelop
(type in X-terminal) Integrated development environment for K. It is really worth downloading (if it does not come with your distribution).

glade
(type in X-terminal) A graphical builder of user interfaces.
"Glade is an interface builder developed by Damon Chaplin. It allows graphical and interactive construction of Gnome/Gtk graphical user interfaces. From Glade, the generated interface can be saved in a xml file or directly exported to C code to be included in a C source tree. Glade also allows to define the name of the handlers - functions - to be attached to the various event of the interface. For example the function (name) to be called when a specific menu item is pressed." (From: http://linuxtoday.com/news_story.php3?ltsn=2000-07-16-013-04-PS-GN)

Related Terms:linux,Simple Programming,Programming,ruby,GNU C compiler ,GNU C,C,g++ filename.C,GNU C++ compiler ,GNU C++,C++ ,kdevelop,glade